First seizure in adolescence revealing hidden bilateral porencephalic cysts

Porencephaly is a rare neurological disorder characterized by cerebrospinal fluid-filled cavities within the cerebral parenchyma. While typically diagnosed in infancy, silent cases may manifest later in life with new-onset seizures. We report a 14-year-old female with a remote history of encephalitis requiring neurosurgical intervention at 8 months of age who presented with her first generalized tonic-clonic seizure. Laboratory evaluation revealed post-ictal leukocytosis and neutrophilia with otherwise unremarkable serum studies. Neuroimaging demonstrated large bilateral porencephalic cysts communicating with the lateral ventricles, accompanied by surrounding gliosis and mild midline shift. The patient remained seizure-free without immediate antiseizure medication and was initiated on levetiracetam for secondary prophylaxis following multidisciplinary consultation. This case highlights that porencephalic cysts can remain clinically silent for over a decade before presenting first-time seizures in adolescence. A history of early brain insult should prompt thorough neuroimaging evaluation, and adherence to contemporary epilepsy terminology is essential for accurate reporting.